This application is based on and claims priority from Japanese Patent Application Nos. 2000-79997, 2000-173699 and 2001-42920 filed on Mar. 22, 2000, Jun. 9, 2000 and Feb. 20, 2001, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an endless track of the type having a ground opposing surface made from rubber and a manufacturing method thereof.
2. Description of Related Art
Various types of endless tracks used for construction vehicles are known, some of which include a ground opposing surface made from rubber for protecting road surfaces.
Such conventional endless tracks of the type having a ground opposing surface made from rubber are grouped into the following three categories:
The first category of the conventional endless track includes an iron link belt 1, an iron shoe 2 and a rubber pad (A-Type) 3, as illustrated in FIG. 14. The iron link belt 1 is provided with the iron shoe 2 which is formed independently of the iron link belt 1. Each iron shoe 2 is provided with the rubber pad (A-Type) 3 including an iron plate 3a and a rubber material 3b, which is adhered to the iron plate 3a through a vulcanization process.
The second category of the conventional endless track includes an iron link belt 1 and a rubber pad (B-Type) 4, as illustrated in FIG. 15. The iron link belt 1 includes a pair of links, to which a plate 4c is welded. The plate 4c is fastened to the rubber pad (B-Type) by a bolt or the like. The rubber pad (B-Type) includes a core metal plate 4a, and a rubber material 4b, which is adhered to the core metal plate 4a through a vulcanization process. The rubber pad (B-type) is directly fixed to the iron link belt 1 without employing an iron shoe. Therefore, the endless track of the second type does not include an iron shoe.
The third category of the conventional endless track includes a rubber crawler 5, as illustrated in FIG. 16. A plurality of iron core plates 5a are embedded in a single rubber belt 5, and the rubber 5b of the rubber belt 5 is adhered to the iron core plates 5a through a vulcanization process, while exposing a part of each iron core plate 5a. The rubber belt 5b extends endlessly. The endless track engages a sprocket at an exposed portion of each iron core plate 5a. Therefore, the endless track of the third category includes neither an iron link belt nor an iron shoe.
Hereinafter, the first category of the conventional endless track will be referred to hereafter as a rubber pad type A, the second category of the endless track will be referred to hereafter as a rubber pad type B, and the third category of the endless track will be referred to hereafter as a rubber crawler type.
The following problems exist in the conventional endless tracks of the type having the ground opposing surface made from rubber.
With the conventional endless track of the rubber pad type A (the first category), rubber needs to be vulcanization-adhered to the iron plate per each of the rubber pads, which requires much time and work, resulting in low productivity.
Further, the conventional endless track of the rubber pad type A requires a large number of members. Thus, the cost is high.
Similarly, with the conventional endless track of the rubber pad type B (the second category), rubber needs to be vulcanization-adhered to the core plate per each of the rubber pads, which requires much time and work, resulting in low productivity.
Although the number of members required for the rubber pad type B is smaller than that of the rubber pad type A because no shoes are included in the rubber pad type B, the rigidity is required all over the rubber pad, so that the manufacturing cost is almost the same as that of the conventional endless track of rubber pad type A.
With the conventional endless track of the rubber crawler type (the third category), the number of the members and the cost are reduced compared with those of the rubber pad type A and the rubber pad type B. However, because a tensile force is borne by the rubber belt only, the life of the rubber belt is relatively short. As a result, breakage of the rubber belt and derailment of the rubber belt are likely to occur during operation.
An object of the present invention is to provide an endless track of the type having a ground opposing surface made from rubber and a manufacturing method thereof, whereby the productivity in vulcanization-forming may be improved, the number of members may be reduced, and the durability may be improved.
The above object can be performed by an endless track and a manufacturing method according to the present invention, as follows:
An endless track includes an iron link belt, a continuous pad and a connecting device. The iron link belt includes a link unit assembly constructed of a plurality of link units connected to each other. Each link unit includes a pair of links.
The continuous pad includes the same number of core metal plates as that of the plurality of link units and a single rubber belt. Each of the core metal plates is fixed to each of the plurality of link units. The rubber belt covers and is vulcanization-adhered to a ground opposing surface of each of the core metal plates. The rubber belt extends continuously over all of the core metal plates.
The connecting device connects the iron link belt and the continuous pad at the link units and the core metal plates.
Each of the pair of links comprises at least one of a bent plate link and a forged link.
The connecting device includes at least one of a bolt-and-nut and a welding.
The connecting device includes the bolt-and-nut, and the bolt-and-nut is welded to the core metal plate and is covered with the rubber of the rubber belt.
Preferably, the iron link belt includes the same number of plates as that of the plurality of link units. Each of the plates is welded to the pair of links of each of the plurality of link units of the link unit assembly and extends perpendicularly to a direction in which the link unit assembly extends. Each of the core metal plates of the continuous pad is fixed to each of the plates of the iron link belt. The rubber belt of the continuous pad includes a small thickness portion between two adjacent core metal plates of the core metal plates. The link belt and the continuous pad are connected to each other by the connecting device at the plates and the core metal plates.
Preferably, each of the core metal plates of the continuous pad extends perpendicularly to a direction in which the link unit assembly extends and is directly welded to the pair of links of each of the plurality of link units of the link unit assembly.
The rubber belt of the continuous pad includes a small thickness portion positioned between two adjacent core metal plates of the core metal plates.
Preferably, the iron link belt includes the same number of plates as that of the plurality of link units. Each of the plates is welded to the pair of links of each of the plurality of link units of the link unit assembly and extends perpendicularly to a direction in which the link unit assembly extends. Each of the core metal plates of the continuous pad is fixed to each of the plates of the iron link belt. The rubber belt of the continuous pad includes a normal thickness portion positioned between two adjacent core metal plates of the core metal plates. The link belt and the continuous pad are connected to each other by the connecting device at the plates and the core metal plates.
Preferably, each of the core metal plates of the continuous pad extends perpendicularly to a direction in which the link unit assembly extends and is directly welded to the pair of links of each of the plurality of link units of the link unit assembly. The rubber belt of the continuous pad includes a normal thickness portion positioned between two adjacent core metal plates of the core metal plates.
A method for manufacturing an endless track includes: (a) connecting a plurality of link units each having a pair of links thereby manufacturing a link unit assembly of an iron link unit; and (b) providing the same number of core metal plates as that of the plurality of link units of the iron link belt and forming a single rubber belt continuously extending over all of the core metal plates such that the single rubber belt covers and is vulcanization-adhered to a ground opposing surface of each of the core metal plates, thereby manufacturing a continuous pad.
Each link of the pair of links is manufactured through at least one of a bending and forging process.
Preferably, during the manufacturing of the iron link belt, a plate extending perpendicularly to a direction in which the link unit assembly extends is welded to the pair of links of each of the plurality of link units of the link unit assembly. During the manufacturing of the continuous pad, before the core metal plates are fixed to the plurality of link units, a small thickness portion is formed between two adjacent core metal plates of the core metal plates when the rubber belt is vulcanization-formed. After manufacturing the continuous pad, the iron link belt and the continuous pad are connected to each other by a connecting device at the plates and the core metal plates.
Preferably, the connecting device includes a bolt and a nut, and before vulcanization-forming of the rubber belt, at least one of the bolt and the nut is welded to each of the core metal plate. During vulcanization-forming of the rubber belt, at least one of the bolt and the nut is covered with a rubber of the rubber belt.
Preferably, each of the core metal plates extending perpendicularly to a direction in which the link unit assembly extends is directly welded to the pair of links of each of the plurality of link units of the link unit assembly of the iron link belt. During manufacturing of the continuous pad, when the rubber belt is vulcanization-formed, a small thickness portion is formed to the rubber belt between two adjacent core metal plates of the core metal plates.
Preferably, during manufacturing of the iron link belt, a plate extending perpendicularly to a direction in which the link unit assembly extends is welded to the pair of links of each of the plurality of link units of the link unit assembly. Before manufacturing the continuous pad, each of the core metal plates is fixed to the plate of each of the link units of the iron link belt. During manufacturing of the continuous pad, the rubber belt is vulcanization-formed such that the rubber belt covers each of the core metal plates and such that a normal thickness portion is formed to the rubber belt between two adjacent core metal plates of the core metal plates when the rubber belt is vulcanization-formed.
Preferably, each of the core metal plates extending perpendicularly to a direction in which the link unit assembly extends is directly welded to the pair of links of each of the plurality of link units of the link unit assembly of the iron link belt. During manufacturing of the continuous pad, a normal thickness portion is formed to the rubber belt between two adjacent core metal plates of the core metal plates when the rubber belt is vulcanization-formed.
Preferably, the method further includes dividing the rubber belt between two adjacent core metal plates of the core metal plates among a plurality of separate pads.